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Can you help me? I have been looking for the flight speed of missiles in space. From Mimi's on up. If you use the Atmo speeds even the slowest merchant ship can out run every missile out there.

In the first edition Robotech game, if a specific space speed wasn't listed, you could increase the listed speeds by 50% or 75%. I've recently interpreted that missile ranges could typically increase by 50% too in space based on texts found in other books for other missiles. (Not to sidetrack the topic, but missiles in general are a subject that are way too oversimplified in Palladium's systems so go crazy fleshing them out)

There are not specific rules about a missile's speed in space vs in atmo. The only differences I found while researching PB's missiles while working on a project was that there were some differences in the area of effect in the nuclear warheads' damages. (These are in the "galaxy" book that details out the structure of the "Center" arcology on phaseworld.)
I agree with tobe that PB's missile rules are very simple and do not account for things like being used in space. This is sort of expected due to that the game is more focused on individual combat on the surface of a planet.
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There are two things to remember.
In both the 3G and the ships of the milkyway galaxy a starship's sub-light speed is quite low.

And due to The Real World, the speeds of the missiles are added to, on top of, the speed of the ship firing them.
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For the Missiles that originate in the 3G, I would apply the HU2 basic rules to them. In that, other then where specified, ALL missiles are self guided and have a +3 to strike.
((Opposed to the RUE rules that say that all missile are NOT self guided, with no bonus to strike.))

My problem is that the fastest missile speed is about Mach 3 and the slowest 3G ship is Mach 5 and most combat vessels are Mach 8-10.

If the ships are going about the same speed and the same direction, the difference between the missile's speed and the ship's speed does not matter. Because the missiles are traveling within the ship's frame of reference and their speed is based on their frame of reference.

so if one ship is pursuing another ship and both are going M10. (keep the numbers round) I ether ship fires it's missiles, say M3, then the missiles will be going M3 in relation to the two ship.

Einstein, Relativity, and all that jazz.

Real world example: say there is a car chase going on between two rival gangs. With both cars going 70 mph (which is about 103 feet per second), and each starts firing their pistols at each other. The pistols (picks a round number out of the air that is close enough) shoot their bullets at 3000 fps. The bullets from the chasing car will be going, in relation to the ground, 3103 fps, but will be only going 3000 fps when compared to the cars. However, the bullets from the car being chased will only be going 2897 fps when compared to the ground's FoR, but when compared to the car's FoR they will also be going 3000 fps.

With the speeds we are talking about ….right now……the more weird effects of Relativity are not in play to a significant amount.

Another thing to remember is that most fights in Phase World are done at basically point blank range.
That missile only has to travel, usually at most, a couple miles tops. That means that as long as your not shooting it at a ship that is running away from you, your likely to be able to hit it.
After all at Mach 3 it will cross a mile in 1.5 seconds... not a lot of time to dodge or shoot it down.

Sure you can't use them on ships that are flying away from you. But that is what your beam weapons are for. But ships flying parallel, at you, on oblique angles, ships trying to stay in energy range, stations, satellites, et multiple cetera missiles are just the thing.

drewkitty ~..~ wrote:If the ships are going about the same speed and the same direction, the difference between the missile's speed and the ship's speed does not matter. Because the missiles are traveling within the ship's frame of reference and their speed is based on their frame of reference.

so if one ship is pursuing another ship and both are going M10. (keep the numbers round) I ether ship fires it's missiles, say M3, then the missiles will be going M3 in relation to the two ship.

Einstein, Relativity, and all that jazz.

Real world example: say there is a car chase going on between two rival gangs. With both cars going 70 mph (which is about 103 feet per second), and each starts firing their pistols at each other. The pistols (picks a round number out of the air that is close enough) shoot their bullets at 3000 fps. The bullets from the chasing car will be going, in relation to the ground, 3103 fps, but will be only going 3000 fps when compared to the cars. However, the bullets from the car being chased will only be going 2897 fps when compared to the ground's FoR, but when compared to the car's FoR they will also be going 3000 fps.

With the speeds we are talking about ….right now……the more weird effects of Relativity are not in play to a significant amount.

I would sort of agree if it weren't for incidents during the Korean War were US (and others) aircraft shot themselves down because their aircraft was faster that the Rockets and bullets that they fired and over ran them.

SpiritInterface wrote:

drewkitty ~..~ wrote:If the ships are going about the same speed and the same direction, the difference between the missile's speed and the ship's speed does not matter. Because the missiles are traveling within the ship's frame of reference and their speed is based on their frame of reference.

so if one ship is pursuing another ship and both are going M10. (keep the numbers round) I ether ship fires it's missiles, say M3, then the missiles will be going M3 in relation to the two ship.

Einstein, Relativity, and all that jazz.

Real world example: say there is a car chase going on between two rival gangs. With both cars going 70 mph (which is about 103 feet per second), and each starts firing their pistols at each other. The pistols (picks a round number out of the air that is close enough) shoot their bullets at 3000 fps. The bullets from the chasing car will be going, in relation to the ground, 3103 fps, but will be only going 3000 fps when compared to the cars. However, the bullets from the car being chased will only be going 2897 fps when compared to the ground's FoR, but when compared to the car's FoR they will also be going 3000 fps.

With the speeds we are talking about ….right now……the more weird effects of Relativity are not in play to a significant amount.

I would sort of agree if it weren't for incidents during the Korean War were US (and others) aircraft shot themselves down because their aircraft was faster that the Rockets and bullets that they fired and over ran them.

In space there is no air resistance, so unless there is some stupid rule about how spaceships can only go Mach 5 or some other unrealistically slow speed number in space, oh geee… wow…. I describing the PB space rules for the 3G.

Your best bet is to use the canon rules, what little there are of them, as a guideline to make rules that work for you.

You might want to check out the space combat rules in the AU:GG book before writing your own rules. They are less unrealistic the the 3G ones. And there are more of them.

I really like relative velocity

it makes sense anyways... battles in the 3g setting are usually more about settling some score or something because basically every race has the power to destroy planets if they ACTUALLY wanted to... but there's nothing to be gained by doing so, so its almost like space-medievalism.

SpiritInterface wrote:Can you help me? I have been looking for the flight speed of missiles in space. From Mimi's on up. If you use the Atmo speeds even the slowest merchant ship can out run every missile out there.

Realistically the missile's max. velocity won't change much, if at all operating in the vacuum of space. All you really get back is any velocity lost due to atmospheric drag.

As others have mentioned there are mentions outside of PW on missile performance modifiers or ones that can be inferred*. Really though as drewkitty~..~ said, it's best to treat the situation as relative for simplicity. When you launch a missile you should add the launch platform's velocity to the missile's (which also has the benefit of increase the range of the missile assuming the engine burns for the same amount of time and their is no "burn and coast" time period).

*ex. MiO pg83 says the range of all missiles double (Mini's, SRM, MRM, LRM). Unless the missiles burn and coast to target, to get double the range would imply that you are going twice as fast if your engine is burning for the same length of time.

I was thinking like.ShadowLogan, multiply speed by whatever range is multiplied by, for simplicity.

Max speed of.missiles in atmosphere would be relates to terminal velocity since both would be I fkuenced by.drag. if the missile.had force.to accelerate more than gravity it could exceed TV.

In space since there is minimal drag (maybe occasional particle of space dust) the max speed should get ridiculous since to maintain a speed in atmosphere would require constant acceleration.

Based.on our limited idea of missile dimensions perhaps we cluks estimate drag and deduce acceleration output for various missiles based in their stated speed.

First the thematic answer; You want missiles to blow people up right? Then they fire from one ship to another pretty fast, but you can dodge them and do crazy stunts through asteroid fields and stuff. This is space opera, it's supposed to look cool.

Below is the ridiculous over-thinking it answer;

When you say 'Speed' the question always has to be 'in relation to what'. Modern Physics recognises that if you are 'falling' towards the earth, it's just as valid to say the earth is moving towards you as it is to say you are moving towards the earth. Because the earth is big, and most objects move in relation to it in our day to day experience, the earth as a stationary reference frame is how we mostly 'treat' stuff. So when we say 'X moves at Speed Y' what we are actually saying is that 'X Moves at Speed Y in relation to the Earth'.

Now Space makes this weird for two reasons; In the Depths of Space, with no major planets or stars around, there is no 'natural' reference frame. Two Ships have speeds in relation to one another that are entirely relative. Assuming no acceleration Ship A could be Moving towards Ship B at 80 m/s, or Ship B could be Moving towards ship A at 80 m/s, or both could be moving towards each other at 40 m/s.

What informs a 'maximum' speed on Earth is the force of friction vs. the force uses to accelerate the object. If your acceleration(and thus Force) is nearly constant, it will cause an increase in Velocity. Friction, as a force that operates in opposition to the direction of motion, increases as velocity increases. So at some point, you reach a point where the force of friction is equal to the force being applied, and you have a 'maximum' speed. That is what terminal velocity is for example; the Velocity at which the force of air friction on a falling body is equal to the force of Gravity, so no acceleration can occur. Now in Space, there is no(or nearly no) Friction, so a 'maximum speed' in this sense makes no sense. If you can provide acceleration forever, you can reach absurd speeds. Eventually, you'll get into relativistic effects and stop out before you hit the speed of light, but that's really beyond what I'm talking about.

But, of course, nothing has constant acceleration forever. You run out of fuel. So most vessels(and missiles) can apply a certain amount of Acceleration over a certain amount of time. This acceleration x time is called(simplification) Delta-V, meaning the maximum change in velocity a ship can execute. This is important because in space, as I discussed, the relative velocity is important.

So here, you have two vessels, one trying to out-run the other. They started off stationary in relation to each other but Vessel A has an acceleration of 10 m/s^2 while B has an acceleration of 8 m/s^2. A rapidly begins to outpace B, after 30 seconds of acceleration A has gotten up to 300 m/s relative to an observing at their original position, and B has gotten to 240 m/s. However, to someone on B looking at A, A appears to be going only 60 m/s and accelerating away at about 2 m/s^2. Realistically what you want in a missile is something that has a high acceleration, say 20 m/s^2. If you launched this it would impact the other craft in about 6 seconds.

Whats the TL/DR part of this? In space it's acceleration and how long you can accelerate for that is important in relative missile combat.

Wise_Owl wrote:First the thematic answer; You want missiles to blow people up right? Then they fire from one ship to another pretty fast, but you can dodge them and do crazy stunts through asteroid fields and stuff. This is space opera, it's supposed to look cool.

Below is the ridiculous over-thinking it answer;

When you say 'Speed' the question always has to be 'in relation to what'. Modern Physics recognises that if you are 'falling' towards the earth, it's just as valid to say the earth is moving towards you as it is to say you are moving towards the earth. Because the earth is big, and most objects move in relation to it in our day to day experience, the earth as a stationary reference frame is how we mostly 'treat' stuff. So when we say 'X moves at Speed Y' what we are actually saying is that 'X Moves at Speed Y in relation to the Earth'.

Now Space makes this weird for two reasons; In the Depths of Space, with no major planets or stars around, there is no 'natural' reference frame. Two Ships have speeds in relation to one another that are entirely relative. Assuming no acceleration Ship A could be Moving towards Ship B at 80 m/s, or Ship B could be Moving towards ship A at 80 m/s, or both could be moving towards each other at 40 m/s.

What informs a 'maximum' speed on Earth is the force of friction vs. the force uses to accelerate the object. If your acceleration(and thus Force) is nearly constant, it will cause an increase in Velocity. Friction, as a force that operates in opposition to the direction of motion, increases as velocity increases. So at some point, you reach a point where the force of friction is equal to the force being applied, and you have a 'maximum' speed. That is what terminal velocity is for example; the Velocity at which the force of air friction on a falling body is equal to the force of Gravity, so no acceleration can occur. Now in Space, there is no(or nearly no) Friction, so a 'maximum speed' in this sense makes no sense. If you can provide acceleration forever, you can reach absurd speeds. Eventually, you'll get into relativistic effects and stop out before you hit the speed of light, but that's really beyond what I'm talking about.

But, of course, nothing has constant acceleration forever. You run out of fuel. So most vessels(and missiles) can apply a certain amount of Acceleration over a certain amount of time. This acceleration x time is called(simplification) Delta-V, meaning the maximum change in velocity a ship can execute. This is important because in space, as I discussed, the relative velocity is important.

So here, you have two vessels, one trying to out-run the other. They started off stationary in relation to each other but Vessel A has an acceleration of 10 m/s^2 while B has an acceleration of 8 m/s^2. A rapidly begins to outpace B, after 30 seconds of acceleration A has gotten up to 300 m/s relative to an observing at their original position, and B has gotten to 240 m/s. However, to someone on B looking at A, A appears to be going only 60 m/s and accelerating away at about 2 m/s^2. Realistically what you want in a missile is something that has a high acceleration, say 20 m/s^2. If you launched this it would impact the other craft in about 6 seconds.

Whats the TL/DR part of this? In space it's acceleration and how long you can accelerate for that is important in relative missile combat.

Keeping it within the game system and simple. From DB2 Phase World pages 160-161 the Broadsword Delta-wing fighter flys at mach 2 in atmosphere and mach 9 in space. RMB page 46 Meduim Missiles travel at mach 1.6-mach 2 in atmosphere but there is no change of velocity in space. The rules for space combat are sorely lacking in basic mechanics on how it is handled, how weapons work and how movement works.

That's what my first answer was for, a more elaborate verson of which would be;

The speed numbers are flavour that don't make any sense. In combat some-one rolls an attack roll for a missile, the other person rolls dodge, or blows it up, or whatever, and their relative speeds never need to enter into it. Either the hit roll hits, or it don't.It's cinematic. If that doesn't make sense, you're left dealing with the fact that in space a 'maximum speed' for an object doesn't make sense unless your talking about the speed of light. 'Realistically' in space, assuming all else being equal, a missile using some form of rocket propulsion would be 'faster' than in an atmosphere because of a lack of atmospheric drag. But realistically we need acceleration to tell us anything useful.

SpiritInterface wrote:My problem is that the fastest missile speed is about Mach 3 and the slowest 3G ship is Mach 5 and most combat vessels are Mach 8-10.

As was pointed out a missile's speed is the speed of the ship at the time of firing plus the missiles speed.

There are a few fan sites that have have the EXATMO speeds of some missiles (especially in the 3-G) at percentages of light / fractional C. Sadly I'm on a rig that doesn't have my bookmarks.
As David Webber would say; the missiles are firing their engines on "sprint-mode" going hundreds of G's acceleration. Unfortunately, none of this smart missile two attacks per turn. At those velocities they'd have ONE chance to strike or they'd be 1/3 an AU past the target before they could even TRY to curve around for a second pass.

DhAkael wrote:snip... Unfortunately, none of this smart missile two attacks per turn. ...snip

I read DW too. And agree with that missiles have but one strike at the end of their run.
Since the smart missiles are said to have 2 APM and are able to dodge PD fire....I take this as that they have two chances per melee to dodge while in flight. Or, if stated in the missile's text. that if they loose target lock, the missile can re-aquire a lock on a random ship... behind the ship they were fired at. This taking an APM, or more, to do.(note that I think only 1st ed RT zent missiles can do this. But I might be incorrect.)

wouldn't the target lock bit require the missiles to have a read sensory instruments skill, to detect possible targets if the initial target is gone or breaks the lock?

And smart missiles would need the same if they are said to be able to dodge an attack directed at it. *shrugs*

As I noted there is only one place that this might be true. I have not examined the 2nd ed RT zent missiles for the find your own target feature.

SpiritInterface wrote:

drewkitty ~..~ wrote:If the ships are going about the same speed and the same direction, the difference between the missile's speed and the ship's speed does not matter. Because the missiles are traveling within the ship's frame of reference and their speed is based on their frame of reference.

so if one ship is pursuing another ship and both are going M10. (keep the numbers round) I ether ship fires it's missiles, say M3, then the missiles will be going M3 in relation to the two ship.

Einstein, Relativity, and all that jazz.

Real world example: say there is a car chase going on between two rival gangs. With both cars going 70 mph (which is about 103 feet per second), and each starts firing their pistols at each other. The pistols (picks a round number out of the air that is close enough) shoot their bullets at 3000 fps. The bullets from the chasing car will be going, in relation to the ground, 3103 fps, but will be only going 3000 fps when compared to the cars. However, the bullets from the car being chased will only be going 2897 fps when compared to the ground's FoR, but when compared to the car's FoR they will also be going 3000 fps.

With the speeds we are talking about ….right now……the more weird effects of Relativity are not in play to a significant amount.

I would sort of agree if it weren't for incidents during the Korean War were US (and others) aircraft shot themselves down because their aircraft was faster that the Rockets and bullets that they fired and over ran them.

In an atmosphere the bullets begin to slow down due to friction as soon as they are fired. If the aircraft is still accelerating it could overtake its bullets. Even more true if you are dealing with ships capable of several times the speed the missiles have. In reality space vehicles should be rated by their acceleration capabilitie. Without atmospheric friction the vehicle will keep accelerating as long as the drives are on. I suggest you ignore physics and enjoy the game.

How about we add speed of missile to speed of ship launching it?

IE if I am chasing a Mach 3 ship and I am traveling Mach 3, my Mach 1 missile goes Mach 4 (3+1) and can catch up?